Patients with seizure disorder controlled by phenytoin that present with seizures and subtheraputic serum concentration require a leading dose of phenytoin in the Emergency Department. There are significant pitfalls with each of three commonly used loading methods includeing inefficacy (oral Phenytoin), adverse reactions (intravenous phenytoin), and drug cost (intravenous phenytoin). The proposed study will be the first controlled, randomized trial comparing these three methods. Clinical, pharmacokinetic and pharmacoeconomic data will be analyzed to determine the most cost-effective method of loading in the Emergency Department.